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#61
19th October 2011
Old 19th October 2011
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Quote:
Originally Posted by Mctwins View Post
Read it and it is noted.

But I am glad that I'm not using QRD diffusor. They seem to develop loobing. Who wants that.

Thanks
oh, dear. there is definitely a lack of understanding with regards to the concepts of the topic. the image was to detail what happens with regards to large arrays (periodic) of the same diffuser.

be glad you aren't using an array of QRD diffusers properly.

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#62
19th October 2011
Old 19th October 2011
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Please explain to me what I don't understand by showing this picture.

First let us make clear that I don't have a QRD and then showing something about QRD and when used in large arrays it creates lobbing.

What is your point. I really dont understand.

Do you think that 3,3 meters of my length of diffusers is a large array??
If QRD have lobbing issues, correct me if I'm wrong, why use it in the first place?? Just a question.

Do I miss something here??

Thanks
#63
20th October 2011
Old 20th October 2011
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Quote:
Originally Posted by Mctwins View Post
No bickering here....
Allright, nagging then... My point was that there is a significant difference between the criteria in a production vs re-production scenario. The goal with a Listening Room (re-production) is to provide the listener with ear-related orgasms! The goal in a Critical Listening Room is to provide the engineer with a reliable listening, so that he may do his work with ease and accuracy i.e. He wants to hear the source material as it really sounds, with minimal alteration.

You've created a space for pleasure listening... and you enjoy the sound... Your job is done!! Whatever coloration your room topology is adding to the sound experience, it serves it's purpose... If you decide to start mixing in there, and you find that your mixes doesn't translate very well, THAT's when you need to start worrying about how to make your system more accurate.

Quote:
Originally Posted by Mctwins View Post
Please explain to me what I don't understand by showing this picture.

First let us make clear that I don't have a QRD and then showing something about QRD and when used in large arrays it creates lobbing.

What is your point. I really dont understand.
The laws of physics do not only apply to QRD's... Lobing Loudspeakers


/Sören
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#64
20th October 2011
Old 20th October 2011
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McTwins,

I invite you to post graphs of your room as per the Chart of Standards in the White Paper I recently co-published. You have done so in most metrics, but doing so in terms of A) comparative ETC and possible inner/intra spectral analysis (which you can do in the RV tab of ARTA) and the overlay of L & R midrange freq response (also available in ARTA).

It is likely that JBL offers the Sound Power Response@2m for your speakers. This could be compared to the L & R midrange freq response. Factor a proper loss due to distance and a conversation on accuracy vs euphonics.

Couple points on speakers: your horn design are likely to retain a constant directivity down toward heart of the midrange which bodes well for accuracy. And you super smooth LF response below 100Hz is a function of the HH devices and mulitple LF drivers across the lower front wall (and for specific reference our paper is specifically pointed to two fullrange speakers in a room...so a bit of difference).

Anyway, as mentioned...I invite you to do so and would enjoy the results.
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#65
24th October 2011
Old 24th October 2011
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Hi Jeff

Give me a day or two to do some measurments.

Thanks
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#66
26th October 2011
Old 26th October 2011
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Hi

I have done some measurements and the mic was placed in a equilateral triangle from the speaker.

Here is first the EDT

Hz; 8000 4000 2000 1000 500 250 125 62,5
Sec; 0,36 0,36 0,34 0,36 0.3 0.28 0.3 0,28

Here is the energy decay sliced in different frequency from the LEFT speaker and it is exactly the same for the right speaker.

1000Hz




2000Hz






4000Hz



8000Hz



Here is a Impulse response between left and right, overlayed.



Thanks, let me know if I have missed something.
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#67
26th October 2011
Old 26th October 2011
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Quote:
Originally Posted by Victor_Stoian View Post
are you also sitting at the tip of that equilateral triangle or is only the mic placed there and your listening place is somwhere else?

Hi

I just want to simulate where an recording engineer is sitting in a studio.
From my point of view I can sit there or farther back in the room, it doesn't matter. The sound is equally good.
But normally I don't sit in the triangle.

I'm just doing some measurments for Jeff.

Thanks
#68
26th October 2011
Old 26th October 2011
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My untrained eye:

there is some early strong energy in the 1 and 2k graphs (but it is unclear if we are truly seeing the direct signal peak on these graphs)

the uneven-ness of the decay is a bit disappointing given the extensive usage of diffusion

Again, untrained, just throwing up an opinion.
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#69
26th October 2011
Old 26th October 2011
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Quote:
Originally Posted by johndykstra View Post
My untrained eye:

there is some early strong energy in the 1 and 2k graphs (but it is unclear if we are truly seeing the direct signal peak on these graphs)

the uneven-ness of the decay is a bit disappointing given the extensive usage of diffusion

Again, untrained, just throwing up an opinion.
When one is going lower in freq it gets harder to see the direct impulse from these graphs.

That's why one have to see the impulse response witch I have provided and shows all freq at once. The overlayed one.

Maybe the uneveness is due to that I have all my equipment between loudspeakers. Maybe I should only have one left/right speaker in this room when measure. Maybe I should measure with a omnidirectional loudspeaker that is normally used in a acoustical measurement.

Lot's of maybes but what do I know.

Thanks
#70
27th October 2011
Old 27th October 2011
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Nicely done McTwins,

Comments (if you don't mind). It would be the point to see your data from your LP.

First, the overlay shows excellent symmetry of energy from L to R. There is not much decay within first 40ms. This is likely do to your closeness between the mic and the speakers and your diffusion. Not a red flag but calls for closer study (the one octave filtered studies).

The one octave studies show a strong balance between the bands shown with a point to be made that 1K is on the edge of being too "hot". It would be proper to compare 500Hz to 1K...but the cause is likely the test location, your ceiling angles and the diffusion...1K should be hotter in that context unless absorption was employed heavily. So my guess is that at your LP, the 1K range will be very much in line with 500Hz and 2K and that there will be surprisingly little trail off at 4K. This is a nice equation for the controlled directivity of your speakers.

Also, a dodec speaker would show things about the room better, but that's not the point...the point is evaluating the speaker/room/listener system.
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#71
1st November 2011
Old 1st November 2011
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Hi, Sorry for the late reply.

Here is measurements in the listening position and right speaker only.

The EDT;

Hz 8000 4000 2000 1000 500 250 125 63
s 0,35 0,36 0,37 0.34 0,3 0.3 0.27 0.28


ETC



1000Hz


2000Hz


4000Hz


8000Hz



EDIT: forgot to mention that the mic is one meter from the Wingdiffusor. The difference I can see is -7dB within 14ms compared to previous graphs. I prefere to listening closer to the Wingdiffusor beacause I gain more info from the music.

I wrote before that I didn't see any difference, but there is, Sorry.

Thanks
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#72
11th November 2011
Old 11th November 2011
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Hi
Can somebody figure out what I have been doing here with these two meaurements.....





....and tell me what the difference is?

I will explain it later

Thanks
#73
11th November 2011
Old 11th November 2011
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ARTA details

Quote:
Originally Posted by Mctwins View Post
... Can somebody figure out what I have been doing here with these two meaurements ... and tell me what the difference is? ...
I guess you've set the Gate length differently in ARTAs Impulse response window. Both FR need longer gate lengths to show the bass range properly. If you can't increase the gate length any more the Sequence length of the measurements might be too short.
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#74
14th November 2011
Old 14th November 2011
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Hi

The seq lenght is measured in 32k periodic. Everything has to do how one sets the cursor and marker in Impulse resp window. For different sets one gets the freq. response accordingly.

If I set cursor within 12 ms I get only the direct response from loudspeaker without the reflection from walls. Then one set longer and compare how the reflection interfere with the response. Very small differences between my two responses.

Thanks
#75
14th November 2011
Old 14th November 2011
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Quote:
Originally Posted by Mctwins View Post
Hi

The seq lenght is measured in 32k periodic. Everything has to do how one sets the cursor and marker in Impulse resp window. For different sets one gets the freq. response accordingly.

If I set cursor within 12 ms I get only the direct response from loudspeaker without the reflection from walls. Then one set longer and compare how the reflection interfere with the response. Very small differences between my two responses.
According to your ETCs, you have a strong early reflection at about 1,5 - 2 ms after direct sound. The minimum gate length in ARTA is 128 samples (2,9 ms if 44,I kHz) so you cannot remove the effect of early reflections using gating.
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#76
14th November 2011
Old 14th November 2011
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Hi

Jens...

You are correct about 128 samples is 2,9s, in my case 2,6s.

But, I am looking at Impulse response not Impulse response envelope(ETC). When set the cursor and the marker, the cursor at direct sound and the marker at 12ms(576samples).

So you mean if I have early strong reflection I can't do this?

Thanks
#77
14th November 2011
Old 14th November 2011
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Quote:
Originally Posted by Mctwins View Post
Hi

Jens...

You are correct about 128 samples is 2,9s, in my case 2,6s.

But, I am looking at Impulse response not Impulse response envelope(ETC). When set the cursor and the marker, the cursor at direct sound and the marker at 12ms(576samples).

So you mean if I have early strong reflection I can't do this?
Since you have a strong early reflection as soon as about 1,5 – 2 ms after the direct sound, you cannot isolate the direct sound since the gate time will need to be shorter than 128 samples in order to not include the strong reflection.

Another thing; use 1/24 octave smoothing when checking the FR. 1/3 hides too much detail.
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#78
14th November 2011
Old 14th November 2011
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Hi
I follow you...

I have checked with 1/24 oct, no major difference.

Thanks
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#79
19th May 2012
Old 19th May 2012
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In this room....











All measured in sweep, sequence lenght 256k.
#80
19th May 2012
Old 19th May 2012
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Cool.
It is very impressing.

The only treatment you have for lower frequencies are the four varitunes?
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#81
19th May 2012
Old 19th May 2012
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No...the 4 V4 is in my down stairs room.


In this room, I have 9 V4(3 behind the speakers and 3 on each side) and 2 DIY V6 with volume like 4 SMT V6. Those DIY V6 takes the first axiell modal resonance around 30Hz and the rest of the V4 around 70-100Hz.

EDIT.Forgott to memtion, that those DIY V6 is behind LP

important to say that Matts(SMT) has not been involved in this rooms treatment.
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#82
19th May 2012
Old 19th May 2012
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Before and after treatment.



the red curve measured without treatment.



here one can see the DIY V6.
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#83
3rd July 2012
Old 3rd July 2012
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There was some question about my Impulse response.

Here it is...

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#84
3rd July 2012
Old 3rd July 2012
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Your measurements don't say much when you're using 1/3 smoothing. Everything looks really good with that much smoothing. Use 1/24 or higher resolution.
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#85
3rd July 2012
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Quote:
Originally Posted by bwo View Post
Your measurements don't say much when you're using 1/3 smoothing. Everything looks really good with that much smoothing. Use 1/24 or higher resolution.
What do you mean, what curve, please specify??
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#86
3rd July 2012
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Frequency response.
And what about posting a waterfall below 400 Hz?
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#87
3rd July 2012
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Quote:
Originally Posted by bwo View Post
Frequency response.
And what about posting a waterfall below 400 Hz?
I mean, come on bwo, you have all the measurments in this thread. Take a look again.
#88
3rd July 2012
Old 3rd July 2012
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I think he is talking about post 82.. BTW did you ever send Ethan your raw files?
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#89
3rd July 2012
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Quote:
Originally Posted by Mctwins View Post
I mean, come on bwo, you have all the measurments in this thread. Take a look again.
Your frequency response is with 1/3 smoothing. Like I said, show 1/24 or higher resolution. Everything looks great with 1/3 oct.
#90
3rd July 2012
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Quote:
Originally Posted by bwo View Post
Your frequency response is with 1/3 smoothing. Like I said, show 1/24 or higher resolution. Everything looks great with 1/3 oct.


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